Q22 - Because the native salmon in Lake Clearwater

[jewels0602]

I'm having trouble eliminating B--

I see why A is the correct answer, but I see B in the same light.

Wouldn't it strengthen the argument if native salmon also compromised two populations that didn't interbreed, giving claim to the fact that the environment is really hardy and really shapes the fishies that live within it.

Is A the correct answer because it takes away another explanation-- that a group of sockeyes interbred with the native salmon pop. which caused the split instead of the environment.

Also, any thoughts on using the negation method on strengthen questions to decide between the answer choices? (Picking the AC that most destroys the argument) I think it might've helped me on this question and it would be a great tool to have in my tool box...

[af10]

No expert here …and about a day out from taking this test so I’ll take some of my frustration out on this question since I seem to suck at most others.

For B – I would argue that this would weaken the argument.

Consider this:

The argument is saying that the once uniform sockeye salmon populations are now different species. They were uniform before but split into two different populations and don’t interbreed anymore. Now that they differ genetically, the researcher concludes that they adapted to their distinct habitat.

Well …if the native Salmon were in two distinct populations and didn’t interbreed, they why are they still a single species? The answer choice tells us that the single populations of native salmon were in these environments, but they obviously didn’t change because, as the answer choice tells us, …it was the native salmon population. This wouldn’t support the hypothesis that they adapted genetically to the habitat.

Correct Answer: A

I think you’ve touched on why A is correct. A is correct because it basically tells us that the difference in genetics isn’t due to breeding between either of the two populations and the native salmon.

[Garychou007]

Task: strengthen
Conclusion: the two genetically distinct new fish adapted to the different habitat.

B) Is wrong because it is OS. We are talking about the new fish here and are trying to strength that the reason for the observed genetic difference is habitat adaption. There can be a million ways to have the genetic variations, interbreeding with original fish for example. What B) tries to do is that it gives us another example of the same phenomenon. It is not a good strengthening strategy if you just plainly give me another example (even though some questions do adopt this strategy).Why it's not a good strategy? Because we are still left hanging without being answered the real cause of this genetic variance. All we got from B) is that the genetic variance is a more widely observed phenomenon.

However, even if we are considering this way of reasoning, B) still requires inference to be a useful strengthening choice. i.e., it needs to explicitly say the native fish also lives in two distinct habitat just like the new fish.

[maryadkins]

Great discussion!

I agree with this post about why (B) is wrong:

The argument is saying that the once uniform sockeye salmon populations are now different species. They were uniform before but split into two different populations and don’t interbreed anymore. Now that they differ genetically, the researcher concludes that they adapted to their distinct habitat.

Well …if the native Salmon were in two distinct populations and didn’t interbreed, they why are they still a single species? The answer choice tells us that the single populations of native salmon were in these environments, but they obviously didn’t change because, as the answer choice tells us, …it was the native salmon population. This wouldn’t support the hypothesis that they adapted genetically to the habitat.

As for "out of scope," it's a tough sell on strengthen and weaken questions because often the correct answer on its face appears out of scope. Take (A) here, for example, which is correct and ALSO about the native salmon.

By the way, great discussion of why (A) does strengthen.

And to answer this question:

Also, any thoughts on using the negation method on strengthen questions to decide between the answer choices? (Picking the AC that most destroys the argument) I think it might've helped me on this question and it would be a great tool to have in my tool box...

Well, think about it. This would be helpful if the correct AC is a necessary assumption. If it's not, it's not going to be that helpful. Sometimes the correct AC to a strengthen question is a necessary assumption but more often it isn't. For this reason, I'm kind of meh on it as a strategy for strengthen questions.

As for the others:

(C) actually IS irrelevant. It doesn't tell us anything about these fish or about how fish might breed.

(D) Hmm. Seems on topic, at least. But wait, how does it affect the hypothesis? We don't know. So nah.

(E) Okay, so it's shrunk. But what would that mean? Too much unknown.

Hope this helps!

[hwangbo.edu]

The LSAT assumes common knowledge, including concepts of natural selection and hypotheses, but what if using those concepts inaccurately make all answer choices seem wrong? I didn't like any of the answers but chose Answer C because it strengthened conditions for supporting the hypothesis. I had eliminated Answer A (the credited response) as a trick answer because it assumed a false dichotomy between breeding (an input of natural selection) and genetic adaptation (an output of natural selection).

Evidence: "sockeyes split into two populations that do not interbreed, one inhabiting deep areas of the lake, the other inhabiting shallow areas."

Hypothesis: "since the the two populations now differ genetically, some researchers hypothesize that each has adapted genetically to its distinct habitat."

Answer C suggests that sockeyes did not necessarily begin genetically adapted to one distinct habitat. Remember, the hypothesis is whether "each has adapted genetically to its distinct habitat." The stimulus infers that the genetically uniform sockeyes, like most types of salmon that inhabit lakes (as per Answer C), had spent time in both areas. However, "something" caused a divergence in both habitat and genetics. The researchers hypothesize the proximate cause as their distinct habitats which, in turn provided the impetus for adapting genetically. Answer C provides a "norm" (control group) from which sockeyes diverged.

Answer A fails to address why the genetically divergent sockeyes inhabit two distinct habitats. Instead, Answer A rules out another cause for the genetic differences - but so what? Again, the hypothesis is whether "each has adapted genetically to its distinct habitat." Couldn't sockeyes have adapted genetically to habitats regardless of breeding - is breeding somehow mutually exclusive with genetic adaptation? In fact, couldn't breeding with a native species have been complementary (expanded gene pool = more potentially advantageous characteristics) and thereby facilitated genetic adaptations to their new habitats?

Usually, when the correct answer is not obvious, one can still arrive at the correct answer by eliminating four incorrect answers. However, for the above reasons, I thought this credited response failed to address (let alone strengthen) the researchers' hypothesis as per the question stem. Maybe I'm missing something so could anyone illuminate other ways to identify the better answer in this situation? Thanks in advance.

[maryadkins]

Couldn't sockeyes have adapted genetically to habitats regardless of breeding - is breeding somehow mutually exclusive with genetic adaptation? In fact, couldn't breeding with a native species have been complementary (expanded gene pool = more potentially advantageous characteristics) and thereby facilitated genetic adaptations to their new habitats?

Agreed. That's why I also struggled to realize why (A) would strengthen at all, and I think you make a fair point about (C), as well...although I still think it's a less good answer compared to (A) because ultimately it has no bearing on the salmon and the lake we're actually talking about, whereas (A) does.

Best not use this question as a model for learning Logical Reasoning techniques is my takeaway. Some questions are just kind of crappy outliers and I'd argue this is one.

[syp]

Hello,

I am still not sure why B is wrong. Can someone please elaborate? Thank you!

[comeau.celina]

I initially got this question wrong, however, upon review i now under stand why.

I could be wrong in my reasoning, but it makes sense to me. I hope it helps some of you.

In the conclusion, it states that each has adapted genetically to its distinct HABITAT. The word habitat is key here, because the author is saying that it is the deep vs shallow habitats that is the cause of the splitting of two distinct groups.

If the Sockeyes and the Native salmon bread, it would be this that resulted in the genetic differences and not adapting to the new habitat. Thats why answer A makes sense. It almost like a defence Necessary Condition question as it rules out a possible alternate explanation, which in turn strengthens the argument.

Hope this helps!!

[andrewgong01]

Great discussion!

I agree with this post about why (B) is wrong:

The argument is saying that the once uniform sockeye salmon populations are now different species. They were uniform before but split into two different populations and don’t interbreed anymore. Now that they differ genetically, the researcher concludes that they adapted to their distinct habitat.

Well …if the native Salmon were in two distinct populations and didn’t interbreed, they why are they still a single species? The answer choice tells us that the single populations of native salmon were in these environments, but they obviously didn’t change because, as the answer choice tells us, …it was the native salmon population. This wouldn’t support the hypothesis that they adapted genetically to the habitat.

I think another way we can easily rule out "B" is simply that it does not get us any closer to answering if the genetic differences is due to the habitat regardless of if the existing native salmon is one or two species or differed genetically.

All "B" tells us is that the native salmon did not interbreed but were they genetically similar or dissimilar? Granted, we can assume "Distinct populations" could be that they are genetically different (OR, distinct can also refer to the fact that one group lives say towards the shores whereas the other group lives near the center of the lake and hence the "Distinct" refers to geography) . Even if we assume the argument means distinct in terms of genetics, are they genetically different because of the environment (as the stimulus would want it to be) or are they genetically different for other reasons (e.g. genetic mutation went down the family line) ? We don't know and hence "B" lacks the ability to strengthen the argument by giving another example to lend credence to the claim in the stimulus. "B" would be more correct if it had said the two distinct populations emerged due to occupying different parts of the lake (which gives more credence to the idea that the environment CAUSES the genetic changes)